US5673121A - Stochastic halftoning screening method - Google Patents

Stochastic halftoning screening method Download PDF

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Publication number
US5673121A
US5673121A US08/663,419 US66341996A US5673121A US 5673121 A US5673121 A US 5673121A US 66341996 A US66341996 A US 66341996A US 5673121 A US5673121 A US 5673121A
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screen
threshold
function
levels
uniformity
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Shen-ge Wang
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Xerox Corp
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Xerox Corp
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Priority to CA002203448A priority patent/CA2203448C/fr
Priority to DE69738441T priority patent/DE69738441T2/de
Priority to JP9150556A priority patent/JPH1079853A/ja
Priority to EP97303978A priority patent/EP0814599B1/fr
Priority to BRPI9703606-4A priority patent/BR9703606B1/pt
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N1/00—Scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission; Details thereof
    • H04N1/40—Picture signal circuits
    • H04N1/405—Halftoning, i.e. converting the picture signal of a continuous-tone original into a corresponding signal showing only two levels
    • H04N1/4051—Halftoning, i.e. converting the picture signal of a continuous-tone original into a corresponding signal showing only two levels producing a dispersed dots halftone pattern, the dots having substantially the same size

Definitions

  • the present invention is directed to a method and apparatus for halftoning gray images represented at a number of levels higher than can be reproduced by an output device.
  • Color in documents is the result of a combination of a limited set of colors over a small area, in densities selected to integrate to a desired color response. This is accomplished in many printing devices by reproducing separations of the image, where each separation provides varying density of a single primary color. When combined together with other separations, the result is a full color image.
  • a separation is conveniently represented as a monochromatic bitmap, which may be described as an electronic image with discrete signals (hereinafter, pixels) defined by position and density.
  • pixels discrete signals
  • density is described as one level in a number of possible states or levels.
  • levels are often termed "gray", indicating that they vary between a maximum and minimum, and without reference to their actual color.
  • Most printing systems have the ability to reproduce an image with a small number of levels, most commonly two, although other numbers are possible.
  • Common input devices including document scanners, digital cameras and the computer imagery generators, however, are capable of describing an image with a substantially larger number of gray levels, with 256 levels a commonly selected number, although larger and smaller levels are possible. It is required that an image initially described at a large set of levels also be describable at a smaller set of levels, in a manner which captures the intent of the user. In digital reproduction of color documents this means that each of the color separations is reduced from the input number of levels to a smaller output number of levels. The multiple color separations are combined together at printing to yield the final color print. Commonly, color documents are formed using cyan, magenta and yellow colorants or cyan, magenta, yellow and black colorants. A larger number or alternative colorants may also be used.
  • Printers typically provide a limited number of output possibilities, and are commonly binary, i.e., they produce either a spot or no spot at a given location (although multilevel printers beyond binary are known). Thus, given an image or a separation in a color image having perhaps 256 possible density levels, a set of binary printer signals must be produced representing the contone effect. In such arrangements, over a given area in the separation having a number of contone pixels therein, each pixel value in an array of contone pixels within the area is compared to one of a set of preselected thresholds as taught, for example, in U.S. Pat. No. 4,149,194 to Holladay.
  • the effect of such an arrangement is that, for an area where the image is a contone, some of the thresholds will be exceeded, i.e. the image value at that specific location is larger than the value of the threshold for that same location, while others are not.
  • the pixels or cell elements for which the thresholds are exceeded might be printed as black or some color, while the remaining elements are allowed to remain white or uncolored, dependent on the actual physical quantity described by the data.
  • the described halftoning or dithering method produces an output pattern that is periodic or quasiperiodic in the spatial coordinates.
  • Dithering creates problems in color document reproduction where the repeating pattern of a screen through the image, when superposed over similar repeating patterns in multiple separations, can cause moire or other artifacts, particularly in printing systems with less than ideal registration between separations.
  • Step 2 is then repeated for all gray levels sequentially.
  • the width of the blue-noise filter varies by an amount corresponding to the current gray level; 4).
  • the summation of dot patterns for each gray levels is the blue noise mask generated.
  • the mask is then used to generate a halftone screen.
  • the result of described sequential design procedure strongly depends on the choice of the seed pattern. If the output is not a satisfactory one, the design procedure has to start over again by choosing different seed or changing the blue noise filter.
  • U.S. Pat. No. 4,485,397 to Scheuter et al. describes a method for generating a non-periodic halftone distribution by determining areas of constant or nearly constant input density and by distributing a precalculated number of print dots inside each area based on a random or pseudo random number and some spatial constraints.
  • the present invention is directed to a method of designing a halftone screen which is based on a function designed to approach an idealized stochastic screen.
  • an idealized stochastic screen is characterized by all of the predominant color dots (black or white) uniformly distributed.
  • the present invention seeks to approach this optimization by iteratively selecting pairs of threshold levels in the screen matrix, and measuring the approach to the idealized stochastic screen.
  • the threshold values are then swapped in position to determine whether the swap improves the measurement or not. If it does, the swap is maintained. The process is repeated a predetermined number of times.
  • a method of designing a halftone cell for converting an images received at d levels, for reproduction at 2 levels, the method including the steps:
  • characterization may be a measurement.
  • the proposed stochastic screen design uses a merit function counting the visual appearance of all gray levels. The same merit function is used throughout the entire optimization process. Also, the new method can apply any existing dithering screen as the start point for further improvement. We believe that this invention promises a better overall quality of dithered halftone images than the conventional design methods.
  • FIGS. 1 and 2 represent a halftoning system in which the present invention finds use
  • FIG. 3 illustrates the improvement of quality Q over the iterative process of the invention
  • FIG. 4 illustrates a flow chart of process for finding the local quality measurement
  • FIG. 5 illustrates the measurement of Rij
  • FIG. 6 illustrates the global quality measurement used to derive an optimized threshold screen.
  • gray image data may be characterized as image signals, each pixel of which is defined at a single level or optical density in a set of ⁇ c ⁇ optical density levels, the number of members in the set of levels being larger than desired.
  • Each pixel will be processed in the manner described hereinbelow, to redefine each pixel in terms of a new, smaller set of ⁇ d ⁇ levels
  • ⁇ c ⁇ and ⁇ d ⁇ are integer values representing pixel depth, or a number of signal levels at which the pixel may appear.
  • One common case of this method includes the conversion of data from a relatively large set of gray levels to one of two legal or allowed binary levels for printing in a binary printer.
  • the term "dot pattern” refers to a product or an image resulting from a screening process.
  • a "screen cell”, as used herein, refers to the set of pixels which together will form the dot pattern, while the term “screen matrix” will be used to describe the set of values which together make up the set of threshold to be applied.
  • a "pixel” refers to an image signal associated with a particular position in an image, having a density between white and black. Accordingly, pixels are defined by intensity and position.
  • a dot pattern is made up of a plurality of pixels. These terms are used for simplification and it should be understood that the appropriate sizing operations have to be performed for images where the input resolution in terms of scan pixels is different from the output resolution in terms of print pixels.
  • color documents are represented by multiple sets of image signals, each set (or separation) represented by an independent channel, which is usually processed more or less independently.
  • a "color image” as used herein is therefore a document including at least two separations, such as in the Xerox 4850 Highlight Color Printer and commonly three or four separations, such as in the Xerox 4700 Color Laser Printer, Xerox 5775 Digital Color Copier, or the Xerox 4900 printer, or sometimes more than four separations (a process sometimes called hi-fi color).
  • One possible digital copier (a scanner/printer combination) is described for example, in U.S. Pat. No. 5,014,123, incorporated herein by reference.
  • Each separation provides a set of image signals which will drive a printer to produce one color of the image.
  • the separations superposed together form the color image.
  • pixels will be used to refer to such an image signal in each separation, as distinguished from “color pixel”, which is the sum of the color densities of corresponding pixels in each separation.
  • Gram as used herein does not refer to a color unless specifically identified as such. Rather, the term refers to image signals which vary between maximum and minimum, irrespective of the color of the separation in which the signals are used.
  • an electronic representation of an original document from image input terminal such as scanner 10 derives electronic digital data in some manner, in a format related to the physical characteristics of the device, and commonly with pixels defined at m bits per pixel.
  • image input terminal such as scanner 10
  • Common color scanners such, for example, Xerox 5775 Digital Color Copiers, or the Pixelcraft 7650C, produce 8 bit/pixel data, at resolutions acceptable for many purposes. Since this is a color document, the image is defined with two or more separation bitmaps, usually with identical resolution and pixel depth.
  • the electronic image signals are directed through an image processing unit (IPU) 16 to be processed so that an image suitable for reproduction on image output terminal or printer 20 is obtained.
  • IPU image processing unit
  • Image processing unit 16 commonly includes a halftone processor 18 which converts m bit digital image signals to n bit digital image signals, suitable for driving a particular printer, where m and n are integer values. It also well within the contemplation of the present invention, to derive images electronically. In such cases, the images may be represented by a page description language file, describing the appearance of the page. In such a case, the IPU might include processing element for decomposition of the page, and color conversions elements for providing appropriate signals for driving a printer.
  • FIG. 2 shows the halftone processor 18 operational characteristics.
  • a color processing system using four separations, C(x, y), M(x,y), Y(x, y), K(x, y), obtained and each processed independently for halftoning purposes to reduce an m-bit input to an n-bit output.
  • the invention is also applicable to the "single separation" or black and white reproduction situation as well. Accordingly, we show a source of screen matrix information, screen matrix memory 106, which provides one input to each comparator 100, 102, 104, 106 and 108 for each separation, where the other comparator is the m bit separation bitmap. The output is m bit output, which can be directed to a printer.
  • This illustration is highly simplified, in that distinct screen matrices may be supplied to each comparator.
  • the average distance of adjacent black pixels should be equal to ⁇ (1-g) -1/2 , where ⁇ is independent of gray levels.
  • ⁇ is independent of gray levels.
  • each white pixel should "occupy" 1/(N-m) or 1/gN, fraction of the total area and the average distance of adjacent white pixels should be equal to ⁇ g -1/2 .
  • An idealized stochastic dithering screen is defined as a threshold mask generating halftone images which satisfy above criterion for all gray levels.
  • the input gray-scale images are specified by integer numbers, G(x, y), where 0 ⁇ G ⁇ M.
  • the dithering screen should have M different threshold values spanning from zero to M-1.
  • N/M elements having the same threshold value T.
  • the ultimate goal of designing a stochastic screen is to distribute the threshold values T so that the resulting halftone images are as close as possible to the ones generated by an idealized stochastic screen.
  • G c Min(T 1 , T 2 ), which requires the largest distance ⁇ (1-G c /M) -1/2 between (x 1 , y 1 ) and (x 2 , y 2 ).
  • d 2 (x 1 -x 2 ) 2 +(y1-y 2 ) 2 ;
  • d c 2 M/ M-Min(T 1 , T 2 )!, if T 2 >M/2 and T 1 >M/2,
  • d c 2 M/Max(T 1 , T 2 ), if T 2 ⁇ M/2, and T 1 ⁇ M/2,
  • the design of stochastic screens becomes a typical optimization problem.
  • the threshold values of a chosen screen are rearranged, the merit function can be evaluated to determine the directions and steps.
  • Many existing optimization techniques can be applied to this approach. The simplest method is to randomly choose a pair of pixels and swap threshold values to see if the overall merit function Q is reduced, Since only those q values related to the swapped pair need to be recalculated, the evaluation of Q does not consume significant computation time.
  • the invention is readily implemented in a general purpose computer, programmed to generate the screen matrix values. Once obtained, the screen matrix values may be readily entered and stored into a halftoning device memory, such as that shown in FIG. 2.
  • One possible embodiment of the invention might take the form of a computer programmed in accordance with the following method, shown in FIG. 4.
  • a given pixel P j located at x j , y j and with threshold value T j , we find its contribution Q j to the total penalty function Q total .
  • All pixels of the given threshold screen with N elements are indexed from 0 to N-1.
  • Each pixel P i is associated with its index i, the spatial location x i , y i and the threshold value Ti .
  • the mean of the gray scale is G mean and the full range of gray scale is G total .
  • index values including i and Q j are set to 0.
  • Value i refers to the index to all pixels other than P j
  • Q j refers to the total contribution by all pairs of P j and P i .
  • Step 404 provides a test wherein each threshold value in the system is compared to the mean gray value for the system, Gmean. If the threshold values are both greater than G mean , g is set to G total -Min ⁇ t i , T j ⁇ at step 406. It the threshold values are both less than G mean , g is set to Max ⁇ t i , t J ⁇ .
  • step 410 for all the spatial replicas of the screen, we calculate the closest distance Rij between Pi and P j .
  • the penalty value q(R ij , g) with gray level g and distance R ij e.g., exp(-C ⁇ R 2 ij ⁇ G total /g).
  • the penalty value q(R ij , g) at the next gray level is recalculated and added to the total contribution Q j . If g>G mean , the value of i is incremented and checked for completion of the iterative process at step 418 and the process is either ended or iterated for the next pixel.
  • FIG. 5 illustrates the measurement of R ij .
  • FIG. 6 shows a flow chart of a process that optimizes the operation for M iterations.
  • m is set equal to 0.
  • j 1 and j 2 are randomly selected. Based on these values, two processes occur, 504) penalty contributions Q j1 and Q j2 are calculated for pixel j 1 and j 2 respectively, and 506) two corresponding threshold values are swapped so that T' j1 is set equal to T j2 and T' j2 is set equal to T j1 .
  • T' j1 and T' j2 we calculate the penalty contribution Q' j1 by pixel j 1 , and the penalty contribution Q' j2 , by pixel j 2 , respectively.
  • step 510 from the calculated penalty values Q j1 , Q j2 , Q' j1 and Q' j2 , we determine whether Q j1 +Q j1 >Q' j1 +Q' j2 . If not, at step 512, we reset T' j1 and T' j2 to their original values. Otherwise, we maintain the new threshold values, and at step 514 we increment m for another iteration and determine whether we have reached a final iteration.
  • threshold screens will be calculated and stored for later distribution as matrices of threshold values. Upon later distribution, these matrices can be downloaded in an appropriate manner into device memories for use as required.
  • the resulting threshold screens may be used for the generation of gray in monochromatic images. They may also be used for the generation of color separations in polychromatic or other multiple separation images. In polychromatic or color images, these stochastic screens may be used exclusively, or in combination with other stochastic or nonstochastic screens, as taught, for example, by U.S. Pat. No. 5,394,252 to Holladay et al.
  • the disclosed method may be readily implemented in software using object oriented software development environments that provide portable source code that can be used on a variety of computer or workstation hardware platforms.
  • the disclosed image processing system may be implemented partially or fully in hardware using standard logic circuits or specifically on a single chip using VLSI design. Whether software or hardware is used to implement the system varies depending on the speed and efficiency requirements of the system and also the particular function and the particular software or hardware systems and the particular microprocessor or microcomputer systems being utilized.
  • the image processing system can be readily developed by those skilled in the applicable arts without undue experimentation from the functional description provided herein together with a general knowledge of the computer arts.
US08/663,419 1996-06-17 1996-06-17 Stochastic halftoning screening method Expired - Lifetime US5673121A (en)

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US08/663,419 US5673121A (en) 1996-06-17 1996-06-17 Stochastic halftoning screening method
CA002203448A CA2203448C (fr) 1996-06-17 1997-04-23 Methode stochastique de demi-teintes de blindage
EP97303978A EP0814599B1 (fr) 1996-06-17 1997-06-09 Tramage en demi-teintes stochastique
JP9150556A JPH1079853A (ja) 1996-06-17 1997-06-09 確率的ハーフトーン化スクリーニング法及び装置
DE69738441T DE69738441T2 (de) 1996-06-17 1997-06-09 Stochastische Halbtonrasterung
BRPI9703606-4A BR9703606B1 (pt) 1996-06-17 1997-06-17 sistema de impressão adequado para formar marcas sobre um substrato e método para projetar uma célula de meio-tom.

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Cited By (55)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5740279A (en) * 1996-11-26 1998-04-14 Xerox Corporation Cluster dot halftoning system
EP0843462A2 (fr) * 1996-11-14 1998-05-20 Xerox Corporation Processus de conception de points groupés de demi-teinte
US5859955A (en) * 1997-01-21 1999-01-12 Xerox Corporation Stochastically clustered dot halftoning system
US6014500A (en) * 1998-06-01 2000-01-11 Xerox Corporation Stochastic halftoning screening method
US6020978A (en) * 1997-09-30 2000-02-01 Lexmark International, Inc. Method and apparatus for color halftoning using interlocked threshold arrays
US6104812A (en) * 1998-01-12 2000-08-15 Juratrade, Limited Anti-counterfeiting method and apparatus using digital screening
US6167147A (en) * 1998-10-26 2000-12-26 The Standard Register Company Security document including pseudo-random image and method of making the same
US6252675B1 (en) 1998-05-08 2001-06-26 Xerox Corporation Apparatus and method for halftone hybrid screen generation
US6304340B1 (en) 1998-11-18 2001-10-16 Xerox Corporation Composite halftone screens with stochastically distributed clusters or lines
US6356363B1 (en) 1997-09-30 2002-03-12 Lexmark International, Inc. Method for halftoning using interlocked threshold arrays or interlocked dot profiles
US6356362B1 (en) 1998-11-02 2002-03-12 Canon Kabushiki Kaisha Halftoning by enhanced error diffusion
US20020102007A1 (en) * 2001-01-31 2002-08-01 Xerox Corporation System and method for generating color digital watermarks using conjugate halftone screens
US6433891B1 (en) 1998-12-14 2002-08-13 Oak Technology, Inc. Stochastic screening method with dot pattern regularity control and dot growth
US6456397B1 (en) 1999-05-12 2002-09-24 Presstek, Inc. Method and apparatus for digital imaging with reduced periodic artifacts using stochastic gradients
US20030128395A1 (en) * 2002-01-07 2003-07-10 Xerox Corporation Color halftoning using a multi-level successive-filling halftone screening alogorithm
US20030128394A1 (en) * 2002-01-07 2003-07-10 Xerox Corporation Color vector halftoning using a successive filling with improved color registration latitude
US20030133160A1 (en) * 2002-01-11 2003-07-17 Xerox Corporation System and method of halftoning for multi-pass rendering
US6671068B1 (en) 1999-09-30 2003-12-30 Sharp Laboratories Of America, Inc. Adaptive error diffusion with improved edge and sharpness perception
US6697169B1 (en) 1999-12-08 2004-02-24 Sharp Laboratories Of America, Inc. Enhanced error diffusion using a correlated chromatic noise pattern
US6707576B1 (en) 1999-12-02 2004-03-16 Sharp Laboratories Of America, Inc. Noise modulation error diffusion of digital halftoning
US20040085588A1 (en) * 2002-10-31 2004-05-06 Xerox Corporation Anisotropic stochastic screen
US6753978B1 (en) 1999-09-22 2004-06-22 Sharp Laboratories Of America, Inc. Higher order error diffusion of digital halftoning
US20040234312A1 (en) * 2003-05-20 2004-11-25 Software 2000 Ltd. Bit mask generation system
US6844941B1 (en) 2000-06-23 2005-01-18 Xerox Corporation Color halftoning using a single successive-filling halftone screen
US6870640B1 (en) 2000-11-16 2005-03-22 Xerox Corporation Method and apparatus for rendering a continuous tone image representation with multiple digital halftoning
US6919973B1 (en) 1999-07-27 2005-07-19 Xerox Corporation Auxiliary pixel patterns for improving print quality
US20050254096A1 (en) * 2004-05-13 2005-11-17 Mani Fischer Reduction of harmonic artifacts in halftone screens
US6970258B1 (en) 1999-07-27 2005-11-29 Xerox Corporation Non-printing patterns for improving font print quality
US20050280873A1 (en) * 2005-09-08 2005-12-22 The Go Daddy Group, Inc. Document color and shades of gray optimization using dithered monochrome surfaces
US20050280872A1 (en) * 2005-09-08 2005-12-22 The Go Daddy Group, Inc. Document color and shades of gray optimization using solid monochrome colors
US20050280874A1 (en) * 2005-09-08 2005-12-22 The Go Daddy Group, Inc. Document color and shades of gray optimization using monochrome patterns
US20050280875A1 (en) * 2005-09-08 2005-12-22 The Go Daddy Group, Inc. Document color and shades of gray optimization using outlining
US7016073B1 (en) 1999-07-27 2006-03-21 Xerox Corporation Digital halftone with auxiliary pixels
US20060066908A1 (en) * 2004-09-10 2006-03-30 Sang-Ho Kim Clustered dot-screen design method, a device to perform the clustered dot-screen design method based on human vision and printer model characteristics, and an image-forming apparatus to output binary images on a designed screen
US20060082829A1 (en) * 2004-10-18 2006-04-20 Software 2000 Ltd. Bit mask generation system
US20060165255A1 (en) * 2005-01-26 2006-07-27 Xerox Corporation Embedding variable watermark information in halftone screens
US20060197992A1 (en) * 2005-03-02 2006-09-07 Xerox Corporation Stochastic screens for rendering devices with high-addressability
US20060279789A1 (en) * 2005-06-10 2006-12-14 Satoshi Yamazaki High-image-quality halftone process
US7286682B1 (en) 2000-08-31 2007-10-23 Xerox Corporation Show-through watermarking of duplex printed documents
US20080019559A1 (en) * 2006-07-21 2008-01-24 Xerox Corporation Digital watermarking process
US20080062447A1 (en) * 2006-09-11 2008-03-13 Xerox Corporation System and method for replacing binary level masks in a page description
EP1936948A2 (fr) 2006-12-22 2008-06-25 Xerox Corporation Procédé pour l'insertion cohérente de filigrane et détection d'images couleur à tramage
US20080246980A1 (en) * 2007-04-04 2008-10-09 Wu-Jie Liao Method for generating basic template utilized to form screening mask
US20100060942A1 (en) * 2008-09-10 2010-03-11 Xerox Corporation Encoding message data in a cover contone image via halftone dot orientation
US20100060943A1 (en) * 2008-09-10 2010-03-11 Xerox Corporation Decoding message data embedded in an image print via halftone dot orientation
US20100282856A1 (en) * 2009-05-06 2010-11-11 Xerox Corporation Method for encoding and decoding data in a color barcode pattern
US20100282851A1 (en) * 2009-05-06 2010-11-11 Xerox Corporation Method for encoding and decoding data in a color barcode pattern
US8564840B2 (en) 2010-05-28 2013-10-22 Xerox Corporation Halftone tiling and halftoning for annular rasters
US8928937B2 (en) 2010-12-22 2015-01-06 Xerox Corporation Method and system for assigning color values to primary colors and secondary colors for color rendering in an inkjet printer
US8970910B2 (en) 2011-12-07 2015-03-03 Xerox Corporation Visible and invisible watermarking of printed images via 2nd generation stochastic seed frequency modulation
US20150092241A1 (en) * 2013-10-01 2015-04-02 Canon Kabushiki Kaisha Image processing apparatus and method for image processing
US9641726B1 (en) 2016-05-06 2017-05-02 Xerox Corporation Multi-ink vector halftoning using multi-bit vector halftoning methods
US9654667B1 (en) 2016-05-06 2017-05-16 Xerox Corporation System and method for stochastic vector halftoning of contone data in a printer having variable printing parameters
US9787871B2 (en) 2015-01-29 2017-10-10 Xerox Corporation Hidden Markov model generation of multi-plane random screens
US9811923B2 (en) 2015-09-24 2017-11-07 Snaptrack, Inc. Stochastic temporal dithering for color display devices

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
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Citations (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4149194A (en) * 1977-07-07 1979-04-10 Xerox Corporation Variable angle electronic halftone screening
US4485397A (en) * 1981-09-12 1984-11-27 Ing. Rudolf Hell Gmbh Method for producing printing forms with irregularly distributed printing points
US4595948A (en) * 1982-10-13 1986-06-17 Ricoh Company, Ltd. Multicolor ink jet recording apparatus having means for preventing blurring of ink
US4876611A (en) * 1986-10-14 1989-10-24 E. I. Du Pont De Nemours And Company Process for recording semihalftone images
US5014123A (en) * 1988-11-25 1991-05-07 Fuji Xerox Co., Ltd. Film image reading system
US5111194A (en) * 1989-02-16 1992-05-05 Ricoh Company, Ltd. Artificial halftone processing apparatus
US5341228A (en) * 1990-12-04 1994-08-23 Research Corporation Technologies Method and apparatus for halftone rendering of a gray scale image using a blue noise mask
US5394252A (en) * 1994-03-02 1995-02-28 Xerox Corporation Hybrid quantization method for color document reproduction
US5438431A (en) * 1992-05-21 1995-08-01 Ostromoukhov; Victor B. Method and apparatus for generating digital halftone images using a rotated dispersed dither matrix
US5489991A (en) * 1992-10-09 1996-02-06 International Business Machines Corporation Method for generating digital halftone images
US5579445A (en) * 1993-12-17 1996-11-26 Xerox Corporation Image resolution conversion method that employs statistically generated multiple morphological filters
US5586203A (en) * 1993-10-04 1996-12-17 Eastman Kodak Company Method and apparatus for generating a halftone pattern for a multi-level output device

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0597596A3 (en) * 1992-10-15 1994-06-15 Digital Equipment Corp Imaging system with translated input levels.
US5317418A (en) * 1993-05-11 1994-05-31 Hewlett-Packard Company Halftone images using special filters

Patent Citations (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4149194A (en) * 1977-07-07 1979-04-10 Xerox Corporation Variable angle electronic halftone screening
US4485397A (en) * 1981-09-12 1984-11-27 Ing. Rudolf Hell Gmbh Method for producing printing forms with irregularly distributed printing points
US4595948A (en) * 1982-10-13 1986-06-17 Ricoh Company, Ltd. Multicolor ink jet recording apparatus having means for preventing blurring of ink
US4876611A (en) * 1986-10-14 1989-10-24 E. I. Du Pont De Nemours And Company Process for recording semihalftone images
US5014123A (en) * 1988-11-25 1991-05-07 Fuji Xerox Co., Ltd. Film image reading system
US5111194A (en) * 1989-02-16 1992-05-05 Ricoh Company, Ltd. Artificial halftone processing apparatus
US5341228A (en) * 1990-12-04 1994-08-23 Research Corporation Technologies Method and apparatus for halftone rendering of a gray scale image using a blue noise mask
US5438431A (en) * 1992-05-21 1995-08-01 Ostromoukhov; Victor B. Method and apparatus for generating digital halftone images using a rotated dispersed dither matrix
US5489991A (en) * 1992-10-09 1996-02-06 International Business Machines Corporation Method for generating digital halftone images
US5586203A (en) * 1993-10-04 1996-12-17 Eastman Kodak Company Method and apparatus for generating a halftone pattern for a multi-level output device
US5579445A (en) * 1993-12-17 1996-11-26 Xerox Corporation Image resolution conversion method that employs statistically generated multiple morphological filters
US5394252A (en) * 1994-03-02 1995-02-28 Xerox Corporation Hybrid quantization method for color document reproduction

Non-Patent Citations (4)

* Cited by examiner, † Cited by third party
Title
Eschbach et al. "Binarization using a Two-Dimensional Pulse-Density Modulation"; J. Opt. Soc. Am. A; vol. 4, No. 10, Oct. 1987, pp. 1873-1878.
Eschbach et al. Binarization using a Two Dimensional Pulse Density Modulation ; J. Opt. Soc. Am. A; vol. 4, No. 10, Oct. 1987, pp. 1873 1878. *
Eschbach; "Pulse-Density Modulator on Rastered Media: Combining Pulse-Density Modulation and Error Diffusion"; J. Opt. Soc. Am. A/vol. 7, No. 4, Apr. 1990, pp. 708-716.
Eschbach; Pulse Density Modulator on Rastered Media: Combining Pulse Density Modulation and Error Diffusion ; J. Opt. Soc. Am. A/vol. 7, No. 4, Apr. 1990, pp. 708 716. *

Cited By (93)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0843462A2 (fr) * 1996-11-14 1998-05-20 Xerox Corporation Processus de conception de points groupés de demi-teinte
US5787238A (en) * 1996-11-14 1998-07-28 Xerox Corporation Clustered halftone dot design process
EP0843462A3 (fr) * 1996-11-14 2003-05-21 Xerox Corporation Processus de conception de points groupés de demi-teinte
US5740279A (en) * 1996-11-26 1998-04-14 Xerox Corporation Cluster dot halftoning system
US5859955A (en) * 1997-01-21 1999-01-12 Xerox Corporation Stochastically clustered dot halftoning system
US6356363B1 (en) 1997-09-30 2002-03-12 Lexmark International, Inc. Method for halftoning using interlocked threshold arrays or interlocked dot profiles
US6020978A (en) * 1997-09-30 2000-02-01 Lexmark International, Inc. Method and apparatus for color halftoning using interlocked threshold arrays
US6104812A (en) * 1998-01-12 2000-08-15 Juratrade, Limited Anti-counterfeiting method and apparatus using digital screening
US6252675B1 (en) 1998-05-08 2001-06-26 Xerox Corporation Apparatus and method for halftone hybrid screen generation
US6014500A (en) * 1998-06-01 2000-01-11 Xerox Corporation Stochastic halftoning screening method
US6167147A (en) * 1998-10-26 2000-12-26 The Standard Register Company Security document including pseudo-random image and method of making the same
US6356362B1 (en) 1998-11-02 2002-03-12 Canon Kabushiki Kaisha Halftoning by enhanced error diffusion
US20020051210A1 (en) * 1998-11-02 2002-05-02 Victor Ostromoukhov Halftoning by enhanced error diffusion
US6870642B2 (en) 1998-11-02 2005-03-22 Canon Kabushiki Kaisha Halftoning by enhanced error diffusion
US6304340B1 (en) 1998-11-18 2001-10-16 Xerox Corporation Composite halftone screens with stochastically distributed clusters or lines
US6433891B1 (en) 1998-12-14 2002-08-13 Oak Technology, Inc. Stochastic screening method with dot pattern regularity control and dot growth
US7099049B2 (en) 1998-12-14 2006-08-29 Zoran Corporation Stochastic screening method with dot pattern regularity control and dot growth
US20030035146A1 (en) * 1998-12-14 2003-02-20 Shenbo Yu Stochastic screening method with dot pattern regularity control and dot growth
US6456397B1 (en) 1999-05-12 2002-09-24 Presstek, Inc. Method and apparatus for digital imaging with reduced periodic artifacts using stochastic gradients
US6970258B1 (en) 1999-07-27 2005-11-29 Xerox Corporation Non-printing patterns for improving font print quality
US6919973B1 (en) 1999-07-27 2005-07-19 Xerox Corporation Auxiliary pixel patterns for improving print quality
US7016073B1 (en) 1999-07-27 2006-03-21 Xerox Corporation Digital halftone with auxiliary pixels
US6753978B1 (en) 1999-09-22 2004-06-22 Sharp Laboratories Of America, Inc. Higher order error diffusion of digital halftoning
US6671068B1 (en) 1999-09-30 2003-12-30 Sharp Laboratories Of America, Inc. Adaptive error diffusion with improved edge and sharpness perception
US6707576B1 (en) 1999-12-02 2004-03-16 Sharp Laboratories Of America, Inc. Noise modulation error diffusion of digital halftoning
US6697169B1 (en) 1999-12-08 2004-02-24 Sharp Laboratories Of America, Inc. Enhanced error diffusion using a correlated chromatic noise pattern
US6844941B1 (en) 2000-06-23 2005-01-18 Xerox Corporation Color halftoning using a single successive-filling halftone screen
US7286682B1 (en) 2000-08-31 2007-10-23 Xerox Corporation Show-through watermarking of duplex printed documents
US6870640B1 (en) 2000-11-16 2005-03-22 Xerox Corporation Method and apparatus for rendering a continuous tone image representation with multiple digital halftoning
US6731409B2 (en) * 2001-01-31 2004-05-04 Xerox Corporation System and method for generating color digital watermarks using conjugate halftone screens
EP1229725A3 (fr) * 2001-01-31 2004-10-06 Xerox Corporation Système et procédé pour générer des filigranes numériques en couleur utilisant des tableaux à demi-teintes
US20020102007A1 (en) * 2001-01-31 2002-08-01 Xerox Corporation System and method for generating color digital watermarks using conjugate halftone screens
EP1229725A2 (fr) * 2001-01-31 2002-08-07 Xerox Corporation Système et procédé pour générer des filigranes numériques en couleur utilisant des tableaux à demi-teintes
US7095530B2 (en) 2002-01-07 2006-08-22 Xerox Corporation Color vector halftoning using a successive filling with improved color registration latitude
US7136189B2 (en) 2002-01-07 2006-11-14 Xerox Corporation Color halftoning using a multi-level successive-filling halftone screening algorithm
US20030128395A1 (en) * 2002-01-07 2003-07-10 Xerox Corporation Color halftoning using a multi-level successive-filling halftone screening alogorithm
US20030128394A1 (en) * 2002-01-07 2003-07-10 Xerox Corporation Color vector halftoning using a successive filling with improved color registration latitude
US7719722B2 (en) 2002-01-11 2010-05-18 Xerox Corporation System and method of halftoning for multi-pass rendering
US20030133160A1 (en) * 2002-01-11 2003-07-17 Xerox Corporation System and method of halftoning for multi-pass rendering
US7139101B2 (en) 2002-10-31 2006-11-21 Xerox Corporation Anisotropic stochastic screen
US20040085588A1 (en) * 2002-10-31 2004-05-06 Xerox Corporation Anisotropic stochastic screen
US7025515B2 (en) 2003-05-20 2006-04-11 Software 2000 Ltd. Bit mask generation system
US20040234312A1 (en) * 2003-05-20 2004-11-25 Software 2000 Ltd. Bit mask generation system
EP1596572A3 (fr) * 2004-05-13 2007-03-14 Hewlett-Packard Development Company, L.P. Réduction des artefacts dans des trames à demi-teintes
US20050254096A1 (en) * 2004-05-13 2005-11-17 Mani Fischer Reduction of harmonic artifacts in halftone screens
US8345311B2 (en) 2004-05-13 2013-01-01 Hewlett-Packard Development Company, L.P. Reduction of harmonic artifacts in halftone screens
US20060066908A1 (en) * 2004-09-10 2006-03-30 Sang-Ho Kim Clustered dot-screen design method, a device to perform the clustered dot-screen design method based on human vision and printer model characteristics, and an image-forming apparatus to output binary images on a designed screen
US8149464B2 (en) * 2004-09-10 2012-04-03 Samsung Electronics Co., Ltd. Clustered dot-screen design method, a device to perform the clustered dot-screen design method based on human vision and printer model characteristics, and an image-forming apparatus to output binary images on a designed screen
US20060082829A1 (en) * 2004-10-18 2006-04-20 Software 2000 Ltd. Bit mask generation system
US8705131B2 (en) 2004-10-18 2014-04-22 Software Imaging Technology Limited Bit mask generation system
US20060165255A1 (en) * 2005-01-26 2006-07-27 Xerox Corporation Embedding variable watermark information in halftone screens
US7436977B2 (en) * 2005-01-26 2008-10-14 Xerox Corporation Embedding variable watermark information in halftone screens
US20060197992A1 (en) * 2005-03-02 2006-09-07 Xerox Corporation Stochastic screens for rendering devices with high-addressability
US20060279789A1 (en) * 2005-06-10 2006-12-14 Satoshi Yamazaki High-image-quality halftone process
US7751088B2 (en) * 2005-06-10 2010-07-06 Seiko Epson Corporation High-image-quality halftone process
US7502135B2 (en) 2005-09-08 2009-03-10 The Go Daddy Group, Inc. Document color and shades of gray optimization using dithered monochrome surfaces
US20050280875A1 (en) * 2005-09-08 2005-12-22 The Go Daddy Group, Inc. Document color and shades of gray optimization using outlining
US20050280874A1 (en) * 2005-09-08 2005-12-22 The Go Daddy Group, Inc. Document color and shades of gray optimization using monochrome patterns
US8179565B2 (en) 2005-09-08 2012-05-15 Go Daddy Operating Company, LLC Document color and shades of gray optimization using outlining
US20080278759A1 (en) * 2005-09-08 2008-11-13 The Go Daddy Group, Inc. Method for Faxing Document Optimized by Using Solid Monochrome Colors
US20080278760A1 (en) * 2005-09-08 2008-11-13 The Go Daddy Group, Inc. Apparatus for Document Optimization Using Solid Monochrome Colors
US20090002768A1 (en) * 2005-09-08 2009-01-01 The Go Daddy Group, Inc. Document Color and Shades of Gray Optimization Using Dithered Monochrome Surfaces
US8253949B2 (en) 2005-09-08 2012-08-28 Go Daddy Operating Company, LLC Document color and shades of gray optimization using dithered monochrome surfaces
US7777917B2 (en) 2005-09-08 2010-08-17 The Go Daddy Group, Inc. Document color and shades of gray optimization using solid monochrome colors
US20050280873A1 (en) * 2005-09-08 2005-12-22 The Go Daddy Group, Inc. Document color and shades of gray optimization using dithered monochrome surfaces
US20050280872A1 (en) * 2005-09-08 2005-12-22 The Go Daddy Group, Inc. Document color and shades of gray optimization using solid monochrome colors
US8115977B2 (en) 2005-09-08 2012-02-14 Go Daddy Operating Company, LLC Document color and shades of gray optimization using monochrome patterns
US20080019559A1 (en) * 2006-07-21 2008-01-24 Xerox Corporation Digital watermarking process
US20080062447A1 (en) * 2006-09-11 2008-03-13 Xerox Corporation System and method for replacing binary level masks in a page description
US7952753B2 (en) * 2006-09-11 2011-05-31 Xerox Corporation System and method for replacing binary level masks in a page description
EP1936948A3 (fr) * 2006-12-22 2009-04-29 Xerox Corporation Procédé pour l'insertion cohérente de filigrane et détection d'images couleur à tramage
US7952767B2 (en) 2006-12-22 2011-05-31 Xerox Corporation Method for coherent watermark insertion and detection in color halftone images
EP1936948A2 (fr) 2006-12-22 2008-06-25 Xerox Corporation Procédé pour l'insertion cohérente de filigrane et détection d'images couleur à tramage
US20080151311A1 (en) * 2006-12-22 2008-06-26 Xerox Corporation Method for coherent watermark insertion and detection in color halftone images
US8243327B2 (en) * 2007-04-04 2012-08-14 Primax Electronics Ltd. Method for generating basic template utilized to form screening mask
US20080246980A1 (en) * 2007-04-04 2008-10-09 Wu-Jie Liao Method for generating basic template utilized to form screening mask
US8023160B2 (en) 2008-09-10 2011-09-20 Xerox Corporation Encoding message data in a cover contone image via halftone dot orientation
US8014035B2 (en) 2008-09-10 2011-09-06 Xerox Corporation Decoding message data embedded in an image print via halftone dot orientation
US20100060943A1 (en) * 2008-09-10 2010-03-11 Xerox Corporation Decoding message data embedded in an image print via halftone dot orientation
US20100060942A1 (en) * 2008-09-10 2010-03-11 Xerox Corporation Encoding message data in a cover contone image via halftone dot orientation
US8100330B2 (en) 2009-05-06 2012-01-24 Xerox Corporation Method for encoding and decoding data in a color barcode pattern
US8047447B2 (en) 2009-05-06 2011-11-01 Xerox Corporation Method for encoding and decoding data in a color barcode pattern
US20100282851A1 (en) * 2009-05-06 2010-11-11 Xerox Corporation Method for encoding and decoding data in a color barcode pattern
US20100282856A1 (en) * 2009-05-06 2010-11-11 Xerox Corporation Method for encoding and decoding data in a color barcode pattern
US8564840B2 (en) 2010-05-28 2013-10-22 Xerox Corporation Halftone tiling and halftoning for annular rasters
US8928937B2 (en) 2010-12-22 2015-01-06 Xerox Corporation Method and system for assigning color values to primary colors and secondary colors for color rendering in an inkjet printer
US8970910B2 (en) 2011-12-07 2015-03-03 Xerox Corporation Visible and invisible watermarking of printed images via 2nd generation stochastic seed frequency modulation
US20150092241A1 (en) * 2013-10-01 2015-04-02 Canon Kabushiki Kaisha Image processing apparatus and method for image processing
US9087291B2 (en) * 2013-10-01 2015-07-21 Canon Kabushiki Kaisha Image processing apparatus and method setting thresholds of dither patterns based on density range and generating binary data depending on thresholds of target pixels
US9787871B2 (en) 2015-01-29 2017-10-10 Xerox Corporation Hidden Markov model generation of multi-plane random screens
US9811923B2 (en) 2015-09-24 2017-11-07 Snaptrack, Inc. Stochastic temporal dithering for color display devices
US9641726B1 (en) 2016-05-06 2017-05-02 Xerox Corporation Multi-ink vector halftoning using multi-bit vector halftoning methods
US9654667B1 (en) 2016-05-06 2017-05-16 Xerox Corporation System and method for stochastic vector halftoning of contone data in a printer having variable printing parameters

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EP0814599A2 (fr) 1997-12-29
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DE69738441T2 (de) 2008-12-24

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